First of all, there is
no way to prove that a hypothesis is
correct. This is a widespread misunderstanding
which educators should probably spend more time
correcting.

Evidence (i.e., results of experiments or
tests) can provide
support for or refute a hypothesis, but
not definitively show correctness. While the
results of a particular test may be in line with a
hypothesis, repeated tests or a different test may
show that a hypothesis is wrong.

As in
this article, the hypothesis of all balls
in a can being white is supported (but not proven)
by pulling out one that is white, and is refuted
(shown to be wrong) by repeating the test and
getting a black ball.

That being said, there is evidence that crop
circles are
not of extraterrestrial origin. For
example, the creators of some of the first modern,
complex crop circles
admitted making them, and subsequent
circles are known to be copycats. Some simpler
crop circles (e.g. plain round circles) are quite
likely made by natural weather phenomena similar
to dust devils.

Answer 2:

That's bad science, but I've also seen the same
bad science in grant proposals asking for lots of
money. You want to test the hypothesis
[the idea]
that crop circles are extraterrestrial. Then you
are being a good scientist, with your mind open to
both Yes and No answers. That can be hard
to do -
to keep your mind open to both Yes and No answers.
We usually want one answer to be true and not the
other answer.

Then you have another problem, if you want to
convince scientists that crop circles are
extraterrestrial. You need to have an
extraordinary amount of evidence - lots more
evidence than if you wanted to convince scientists
that crop circles come from things that happen on
Earth, because that's easier to believe.

An example of this is that it's easy for people to
believe that you saw a horse, but it's hard for
people to believe that you saw a unicorn. So you
need to have lots more evidence that you saw a
unicorn, and that's hard to get.